Power line alarm responsive to plural current interruptions in a predetermined time



March 8, 1966 R, sc n- 3,239,830

POWER LINE ALARM RESPONSIVE TO PLURAL CURRENT INTERRUPTIONS IN APREDETERMINED TIME Filed Dec. 24, 1959 2 Sheets-Sheet 2 INVENTOR ROBERTT SCH/W77 ATTORNEYS United States Patent 3,239,830 POWER LINE ALARMRESPONSIVE TO PLURAL CURRENT INTERRUPTIONS IN A PREDETER- MINE!) TIMERobert T. Schmitt, 15554 Mercury Drive,

Grand Haven, Mich. Filed Dec. 24, 1959, Ser. No. 462 7 Claims. (Cl.340-310) This invention relates to a universal, emergency alarm system.More particularly, it relates to an alarm system for use in conjunctionwith the community electrical power system.

This application is a continuation-in-part of United States patentapplication Serial No. 836,378, filed August 27, 1959, by Robert T.Schmitt for Universal Emergency Alarm System, now abandoned.

The need and problem of alerting the people of a community to a nationaland local emergency situation has become most acute within recent years.Advancements in weather forecasting and sighting have made possible thegiving of advance notice to communities of hurricane and tornadoconditions. For this a warning system is needed. Advancements in nuclearenergy warfare and in intercontinental ballistic missiles also makenecessary a community warning system.

Attempts have been made to solve this problem. Thus, in many communitiesthere have been provided sirens at strategic locations within thecommunity, which sirens are under the control of the local police or ofthe local civil defense authorities. Of course, giving warning by meansof public announcements over radio and television is also being done.

However, none of these ways of alerting and warning a community are aseffective as desired. A substantial share of the population of a localcommunity may not have their radio and television sets turned on at thetime a local emergency is announced. This is especially true at night.Many people are such sound sleepers that the sound of sirens in thedistance will not awaken them. Then, too, in many communities the sirenis also used to summon volunteer firemen with the result that a largeproportion of the population of these communities are not likely toattach any more significance to the sound of sirens than that volunteerfiremen are being summoned. Hence, there is still a need for a communitywarning system which will reach into the home of every individual withinthe community and which will have special significance to the effectthat a local or national emergency is at hand.

One approach to this problem of alerting all of the people in acommunity to a local or national emergency is to utilize the communityelectrical power system. This approach is feasible, and, indeed, hasbeen suggested before, because there are few homes, if any, which do nothave connections to the community electrical power system. The solutionsto this problem which have been proposed and which are based on thisapproach are unsatisfactory, however, for a variety of reasons. A chiefreason is that the devices used are too complicated and thus tooexpensive for community-wide acceptance. An other reason is the chanceof failure of the devices proposed. Still another reason is thatspurious interruptions of electrical current in community electricalpower systems, which may be the result of natural causes such aslightning and the like, and the result of mechanical causes such asautomatic relays and overload switches in the electrical system, actuatethe warning devices to give false warnings frequently enough to makesuch devices unreliable.

A general object of this invention is to provide an Patented Mar. 8,1965 emergency alarm system which can be placed in every house andbuilding in a community and which is actuated by purposefulinterruptions in the community electrical power system.

A specific object of this invention is to provide a warm ing systemwhich is simple in operation and in structure.

Another specific object of this invention is to provide a home alarmdevice which will give warning of local and national emergencies andwhich need be merely plugged into a convenient electrical outlet in thehome.

These and other objects which may appear as this specification proceedsare achieved by this invention which shall be described in the contextof the drawings which form a material part of the disclosure. A brieflisting of the drawings is as follows.

FIG. 1 is a perspective view of the outside of a preferred embodiment ofthe warning device of this invention.

FIG. 2 is a schematic diagram of the electrical circuitry involved inthe preferred embodiment of the warning device of this invention.

FIG. 3 is a top perspective View of a portion of an alternativeembodiment of this invention.

FIG. 4 is a circuit diagram of the alternative embodiment shown in FIG.3.

The drawings broadly disclose an alarm actuating circuit which isoperable merely upon the line cord thereof being plugged into a suitablewall socket connected to the community electrical power supply system.The heart of the unit is a switch responsive to a predetermined number,greater than one, of interruptions in the community electrical powersupply for completing the circuit between an electrical power supplysource and an electrically operated alarm. The power source may bebatteries or the community electrical power supply. The alarm can be abell, buzzer, light, radio and the like, even including sirens. Meansare provided for resetting the switch in the event of spuriousinterruptions in the community power supply and in the event theemergency for which the alarm was given has ceased.

Interruption, as uesd in this application, means a decrease variation inthe standard electrical power which can include cutting off the powerentirely or substantially decreasing it to an amount necessary to causethe alarm device to operate in the desired manner.

Structure The drawings specifically disclose an alarm unit 10 comprisinga housing or alarm box 11. Extending out from the alarm box 11 is aconventional two-wire electrical line cord 12 with plug. In additionthere may be provided one or more two-wire electrical cables, such ascables 13 and 14, coupled as by Way of phone jacks and plugs to theelectrical circuitry and components within the alarm box 11 and leadingto various types of alarms. On an exposed face of the alarm box 11 thereis provided a normally closed test switch 15 and an indicator light 17.

Within the box 11 there is provided an electrical switch component 18and an automatic reset switch 19 (FIG. 2). There may also be includedwithin the box 11 electrically operated alarm. means including batterypowered alarm means. However, in the embodiment shown in the drawings,the alarm means are located externally of box 11. Also located withinthe box 11 are the various electrical leads and wiring for electricallyconnecting together the various components of the alarm system in themanner to be described in the paragraphs which follow.

The line cord 12 comprises a pair of electrical leads 20 and 21. Linecord lead 20 is connected to a first terminal of the test switch 15. Theother line cord lead 21 is connected to a first end of a fuse 22.

The electrical switch component 18, which may be termed a step relayswitch, comprises a rotatable switch arm 24 in combination with a relaysolenoid 25 and a reset solenoid 26. The arm 24 is rotatable stepwisefrom one position or point to the next.

Preferably, it has a first position, a last position and a number ofintermediate positions. These positions are indicated in the drawings bycontacts 27, 28, 29, 30, 31, 32 and 33 with contact 27 being at thefirst position and contact 33 being at the last position. When currentflow through the relay solenoid 25 is interrupted, the switch arm 24moves from one contact to the next, proceeding stepwise with eachcurrent interruption from contact 27 to contact 33. However, whenelectrical current flows through the reset solenoid 26, the switch arm24 returns to its first position at contact 27.

Contacts 28, 29 and 30, it will be observed, are electrically connectedtogether by jumper wires 34 and 53. Moreover, contacts 31 and 32 areelectrically connected together by a jumper wire 54.

Relay solenoid 25 has two terminals, the first one of which is connectedby electrical lead 35 to the second terminal of the test switch 15, thesecond one of which is connected by electrical lead 36 to the second endof the fuse 22. Also connected as by electrical leads 37 and 38 to saidfirst terminal of the relay solenoid 25 is the switch arm 24.

Reset solenoid 26 likewise has a first terminal and a second terminal.The first terminal thereof is connected as by way of electrical leads 39and 40 to said second terminal of relay solenoid 25. The second terminalthereof is connected as by way of electrical lead 41 to the contact 33of the electrical switch component 18.

The indicator light 17, preferably of the neon type, has a first and asecond terminal, the first of which is connected by electrical lead 42to the contact 27 and the second of which is connected as by electricalleads 43 and 40 to said second terminal of the relay solenoid 25.

The automatic reset switch 19 comprises a resistance type heater element56, a variable resistor 57 and a normally open, heat sensitive switcharm 58 with a contact 59. One terminal of the heater element 56 iselectrically connected to the switch arm 58 and as by an electrical lead60 to contact 28 of the step relay switch component 18. The otherterminal of the heater element 56 is electrically connected to oneterminal of the variable resistor 57. The other terminal of the variableresistor 57 is electrically connected as by electrical leads 61, 39, 40and 36 and the fuse 22 to the line cord lead 21. The contact 59 iselectrically connected as by an electrical lead 62 to the secondterminal of the reset solenoid 26. When current flows through the heaterelement 56, heat is generated, thereby causing the heat sensitive switcharm 58 to move towards its contact 59. When a predetermined temperaturehas been reached, which is a function of time, the switch arm 58 willtouch the contact 59. By suitable adjustment of the variable resistor57, the time involved for the switch arm 58 to strike the contact 59,once current starts to flow through the heater element 56, can beregulated.

The alarm cable 13 depicted in FIG. 1 extends to a 110 volt A.C. poweredalarm. The cable 13 comprises a pair of electrical leads 46 and 47 (FIG.2). The electrical lead 46 is connected via electrical lead 40 to saidsecond terminal of the relay solenoid 25 while the electrical lead 47 isconnected to the contact 31. Connected across these leads 46 and 47outside of the box 11 (or inside of the box in other embodiments) may bea buzzer or bell 48, a light 49 and the like.

The alarm cable 14 depicted in FIG. 1 extends to a battery poweredalarm, and includes a pair of electrical leads 50 and 47 (FIG. 2). Thelead 47 of the alarm cable 14 is electrically common to the lead 47 ofthe alarm cable 13 because of the common connection to the contact 31 ofthe electrical switch component 18.

Hence, separate leads are not shown although in actual practice separateleads would be used. The lead 50 is electrically connected as by way ofelectrical lead 38 to the switch arm 24. Connected across the leads 47and 50 outside of the box 11 (or inside of the box in other embodiments)is a battery powered alarm such as a battery and bell 51 in series, abattery and light 52 in series, and the like.

Operation To use the alarm unit 10, the same is placed at a convenientlocation and the line cord 12 plugged into any suitable electricaloutlet associated with the community electrical power supply system,whereby the relay solenoid 25 is energized. At this point, if switch arm24 happens to be on contact 27, the indictaor lamp 17 will light up. Ifswitch arm 24 happens to be on contacts 28, 29 and 30, the reset switch19 will be closed after a predetermined period of time has elapsed,causing the reset solenoid 26 to be energized and thereby causing switcharm 24 to be in contact with position contact 27, lighting the indicatorlamp 17. In other words, when alarm unit 10 is plugged in, it willautomatically reset itself to contact 27 by means of the time delayswitch 19 if the arm 24 happens to be resting on contacts 28, 29, or 30.

If a volt A.C. powered alarm such as the bell 48, light 49 and the likeis to be used, the alarm cable 13 therefrom is plugged into theappropriate jack in the box 11. If a battery powered alarm is to be usedinstead, the alarm cable 14 therefrom is plugged into the appropriatejack in the casing 11. Usually, the two types of alarms will not be usedtogether. However, such can be done and for that reason both alarmcables 13 and 14 are shown plugged into the suitable jacks of the alarmunit 10 in FIG. 1. If the arm 24 happens to be on contacts 31 or 32after the unit 10 is plugged in, then the alarms will sound. By pushingthe test switch 15 one or more times, the switch arm 24 is advanced toits contact 33 at which point the reset solenoid 26 is energized. Thiscauses arm 24 to return to its first position contact 27, therebylighting indicator lamp 17. Thus, in any event, the warning system isnow in operation.

When it is determined that a national or local emergency exists, theelectrical utilities in the affected areas are notified as by directtelephone. Immediately, the power plant operators interrupt the power apredetermined number of times. In the embodiment shown, thepredetermined number is four. However, this number may be more and lessthan four, but it will always be greater than one. Preferably, however,it is four or more because in many communities, the relay and overloadmechanisms associated with the community power system may create innormal operation up to three momentary interruptions in electrical powerto the community. Hence, five or more contact positions in theelectrical switch component 18 are preferred wherefore the electricalpower is preferably interrupted four or more times when it is desired togive warning of a national or local emergency.

With each interruption of the community electrical power supply, therelay solenoid 25 is de-energized and the switch arm 24 advances fromone contact to the next. When, as in the case of the embodiment shown inthe drawings, four momentary interruptions have occurred, the switch arm24 will be in touch with its contact 31 whereby the electrical circuitof the 110 volt A.C. powered alarms 48 and 49 is completed. The audibleand visual alarm is thereby given. The individual receiving the alarmcan immediately head for shelter and turn on his radio to a local orConelrad frequency for information as to the nature of the emergency.This entire procedure can take place within a matter of seconds.

When the national or local emergency ceases, or after any predeterminedperiod of time, the power station operator again momentarily interruptsthe electrical power to the community a predetermined number of timeswhich, in the case of the embodiment shown in the drawings, is two. Witheach interruption, the relay solenoid 25 is de-energized, causing theswitch arm 24 to advance from one contact to the next. In advancing fromcontact 32 to contact 33 the circuit of the 110 volt operated alarms 48and 49 and the circuit of the battery operated alarms are broken. Whenthe switch arm 24 touches the last contact 33, the circuit of relaysolenoid 26 with the 110 volt, community power supply is completed andsolenoid 26 is energized. The switch arm 24 thereupon is returned to itsfirst contact position and into touch with its contact 27 whereupon theindicator light 17 commences to glow. The alarm unit is then ready forthe giving of another alarm.

As already indicated, spurious interruptions in the power supply to thelocal comunity may occur. When such happens, the switch arm or armature24 will, of course, move out of touch with its first contact 27 to thenext contact 28, and possibly even from the contact 28 to contacts 29and 30 depending upon the number and timing of the spuriousinterruptions. However, because the contacts 28, 29 and 30 are connectedtogether by the jumper wires 53 and 34 and electrically connected to thereset switch 19 by the lead 60, the circuit of the heater element 56 iscompleted. After the predetermined period of time as established by thevariable resistor 57 has elapsed, the reset switch arm 58 will close,causing the reset solenoid 26 to be energized and thus the switch arm 24to be returned into position in touch with the first position contact27. Thus, the alarm device is completely automatic and once plugged inwill always maintain itself in its proper position. This is especiallyimportant in that without the automatic reset feature, it is conceivablethat a power company might heve several spurious interruptions duringthe night, causing the switch arm 24 in all alarm units to advance toposition 29 or 30. Then if an actual emergency were to arise before thepublic had a chance to reset their alarm units 10, the normalinterruption procedure from the power company would carry arm 24 pastthe alarm actuating contacts 31 and 32, thus causing the device to beunable to give the necessary alarm.

The period of time or delay time in which the reset switch arm 58 closesis selected with the period of time needed to give an alarm with thisinvention in mind. The delay time should be at least slightly greaterthan the period of time needed by the power plant operator to interruptthe community power supply the prescribed number of times. Generallyspeaking, the delay time will be about fifteen to thirty seconds. Withdelay time selected, the variable resistor 57 is adjusted until thedelay 0 time condition is met. This is a factory adjustment.

As can be seen, the number (n) of interruptions and the number (n+1) ofpositions through which the switch arm 24 must move before completingthe 110 volt circuit or the battery circuit of the alarm means isselected according to the number of spurious interruptions as wouldlikely occur between resettings. Generally speaking, the number (n+1) isgreater than one. Preferably, the number (n) is four. However, it may befive and greater. In addition, the number m of contact positions fromthe n+1 contact position to the contact position at which the solenoid26 circuit is completed can be any number. In the embodiment shown, itis two. Preferably, it is the last contact position of which the switcharm 24 is inherently capable of reaching. Hence, there may be more thanone contact position for the switch arm 24 between the n+1 contactposition at which the alarm electrical circuits are completed and thecontact at which the reset solenoid 26 electrical circuit is completed.From the foregoing, it will be apparent that the switching positionrepresented by contact 27 may aptly be termed an inactive or resetposition, the switching positions represented by contacts 28, 29, and 30may be termed active switching position preceding the alarm-actuatingswitching positions, the switching positions represented by contacts 31and 32 may be termed the alarm-actuating positions, and the switchingposition represented by contact 33 may be termed an active switchingposition succeding the alarm-actuating positions.

It is contemplated that a spurious interruption in the community powersystem or in portions thereof may occur just before alarm is to be givenand within the time delay period established by the time delay switch19. Hence, as a saftey factor, the jumper wire 54 between contacts 31and 32 of the embodiment of FIG. 2 is provided. In other embodiments,wherein more than two contact positions for the switch arm 24 areinvolved between the contact 31 and the like and the contact 33 and thelike, the electrical lead 47 may be connected to more than one of theseintermediate contacts. Hence, if the switch arm 24 prior to the givingof the emergency signal is resting on, for example, contact 28, and thepower plant operator interrupts the community power supply theprescribed number of times, n, in this instance four, the switch arm 24will still complete the electrical circuit of the 110 volt A.C. operatedalarm and of the battery powered alarms as the case may be. By providingthe contact for completing the circuit of the reset solenoid 26 at theend of the series of contact positions of the switch arm 24, when theemergency is over and the power plant operator interrupts the communitypower supply the prescribed number of times, m, for turning off thealarms and for resetting the alarm box, the switch arm 24 regardless ofwhether it be on the contact 31 or 32 will nevertheless come intocontact with the last position contact 33, thereby energizing the resetsolenoid 26 and returning the switch arm 24 to its first positioncontact 27.

A simplified embodiment of this invention is shown in FIGS. 3 and 4.Turning first to FIG. 4, the connection to the power line is once againshown as 20, 21. The test switch 15 is normally closed and, when opened,interrupts the current normally supplied to the coil 25 of switch 18.Switch 18 is shown in detail in FIG. 3 and consists basically of a blockriding in a U-shaped track 102 and movable therein from left to right inthe perspective of FIG. 3. A spring 104 biases block 100 to the left,but a pawl 106 engaging teeth 108 of block 100 prevents the block 100from moving to the left. The coil 25 of the switch acts as a solenoidwhich holds the core 110 to the left when current is supplied to thecoil 25. A spring 112 attached to the core 110 tries to pull the core110 to the right, but is overpowered by coil 25 as long as current fiowsthrough coil 25. The core 110 terminates in a pawl 114 which is biasedin a downward direction in FIG. 3 by suitable biasing means (not shown).When the core 110 is withdrawn into the coil 25 as far as it will go,the edge 116 of pawl 114 rests on the surface of plate 118 as shown inFIG. 3 and is prevented thereby from engaging the teeth 120 of block100. If the electric current through coil 25 is now cut off, the spring112 pulls core 110, and with it pawl 114, to the right, until edge 116of pawl 114 rides over the edge 122 of plate 118 and, being biased in adownward direction, drops down to engage the teeth 120 of block 100.After engaging the teeth 120, pawl 114 continues its travel to the rightunder the influence of spring 112 until it is prevented from furthermovement to the right by hitting edge 124 of plate 118.

The block 100 carries on its upper surface a contact strip 126 which ispreferably convex so as to engage corresponding contact strips 128mounted on the inside of the cover 130 of the device 10. The electricalconnections to strips 126 and 128 areshown in FIG. 4, from which it willbe readily apparent that strip 126 is in effect the movable contact of amulti-position switch 18, whereas contacts 128 are the fixed contacts ofthe same multi-position switch 18. (The cover 130 and strips 128 areshown in phantom lines in FIG. 3 so as not to obscure the remainder ofthe mechanism.) The size of the teeth 120 and the distance between theedges 122 and 124 of plate 118 are so designed that each time a powerfailure occurs, the pawl 114 will move block 100 to the right by exactlythe distance between the centers of two adjacent contacts 128.Appropriate stops (not shown) are provided in channel 102 so that ifblock 100 is moved as far to the left in FIG. 3 as it will go, it is insuch a position that when the cover 130 is affixed to the device 10,contact strip 126 will be in contact with contact strip 128a. The firstpower interruption will cause contact strip 126 to move into engagementwith contact strip 12%; the second power interruption will cause it tomove into contact with strip 1230, etc. In each instance, movement tothe left of block 100 under the influence of spring 104 is prevented bypawl 106 engaging teeth 108 of the block 100. If less than 11 powerinterruptions occur, electric power will be supplied through wire 132 tothe coil 134. The coil 134 is wrapped around the shank 136 of pawl 106.The shank 136 is made of bimetal strip, and the coil 134 is so designedthat it will gradually heat up when traversed by current, so that whenit is energized, it will cause the bimetal strip 136 to heat up anddistort downwardly in FIG. 3, thus disengaging the pawl 106 from teeth108. When the pawl 106 has become completely disengaged from teeth 108,spring 104 is free to return block 100 to its initial leftmost positionwhere contact strip 126 is in contact with contact strip 128a on cover130. Thus, it will be seen that the thermal latch 106, 134, 136,together with spring 104 performs the same function as the reset coil 26of the embodiment of FIG. 2. An alarm buzzer 138 may also be providedfor purposes of testing or for alarm purposes if the device is notconnected to any outside alarm system. The output 46, 47, 50 of thedevice of FIG. 4 serves the same purpose as the output of like numbersof the circuit of FIG. 2.

In operation, successive power failures at short intervals will causepawl 114 to engage teeth 120 of block 100 and move it to the right stepby step so that contact strip 126 successively comes in contact witheach of the contact strips 128. If a sufficient number of power failuresoccur before coil 134 has had time to heat the metal strip 136sufficiently to cause pawl 106 to snap out of engagement with teeth 108,strip 126 will eventually come in contact with contact strip 128e andwill cause the alarm to sound. At the same time, the circuit of coil 134is cut and the device can no longer reset itself until further currentinterruptions cause the device to move to the final contact strip 128gat which the alarm is deenergized and power is returned to coil 134 soas to cause the devise to reset itself.

Thus, there is presented a simple and yet most effective and practicalalarm system. Its inherent simplicity leads to speed in notifying thepublic of emergency situations. The alarm box is small, compact, andsimple in structure. The alarm box, therefore, can be readilymanufactured at economical prices. Hence, it should be possible for eachhome to have several alarm units.

The alarm actuating unit 10, once the line cord 12 is plugged into anysuitable electrical outlet, is constantly on duty, day and night. Thereis nothing to adjust and no tubes to burn out. No maintenance isrequired. All that is needed is an occasional glance at the alarm box tomake certain that the indicator light 17 is glowing.

A major advantage of the alarm system of this invention is that noperiodic mass testing is needed. Each individual can test his own alarmboxes by merely pushing the test switch to interrupt the electricalpower to the alarm box the prescribed number of times.

Still another major advantage is that the alarm box can be installedanywhere either indoors or out wherever community power is available.The system is the simplest yet devised for alerting motorists orpedestrians on the streets and highways who might not have their radioson or other indicating devices to alert them. Moreover,

the alarm box can be used to operate air raid sirens and other publicalarm or indicator devices in any emergency.

These and other advantages will be apparent to those in the exercise ofordinary skill in the art upon reading the foregoing description. Inaddition, this invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof.Consequently, the embodiments just described are illustrative and notrestrictive since the scope of the invention is defined by the appendedclaims rather than by the description preceding them.

I claim:

1. In a community alarm system responsive to a predetermined number ofinterruptions of the community power supply within a predetermined time,a movable member, a movable contact mounted on said movable member,biasing means biasing said movable member in said direction, latch meansfor preventing movement of said movable member in said first direction,advancing means engageable with said movable member and biased formovement in a second direction, electromechanical means connected tosaid community power supply for holding said advancing means out ofengageemnt with said movable member when said community power supply isenergized, a plurality of fixed contacts successively engageable by saidmovable contact upon movement of said movable member, limit means forlimiting movement of said movable member by said advancing means to thedistance between two of said fixed contacts each time said communitypower supply is deenergized, and time delay means operative to releasesaid latch if less than said predetermined number of power interruptionoccur within said predetermined time.

2. An electrical alarm system for connection with a community powersystem for giving warning of local and national emergencies, whichcomprises: stepping switch means responsive to at least n interruptionof electrical current in said power system, it being a predeterminednumber greater than 1, said switch means including movable arm meansconnected to the first side of said power system, said switch meansfurther including contact positions from a first position to at least ann+1+m position, m being a predetermined whole number, alarm meansconnected to the n+1 position contact and to the second side of saidpower system, relay solenoid means connected across said power systemfor stepping said arm through the contact positions in response tointerruptions of said electrical current, and reset means forautomatically returning said arm to said first position from any of saidn positions upon prolonged contact therewith.

3. An electrical alarm system for connection with a community powersystem for giving warning of local and national emergencies, whichcomprises: stepping switch means responsive to at least n interruptionsof electrical current in said power system, It being a predeterminednumber greater than 1, said switch means including movable arm meansconnected to the first side of said power system and further includingcontact positions from a first position to at least an n+l+m position, mbeing a predetermined whole number, alarm means connected to the n+1position contact and to the second side of said power system, relaysolenoid means connected across said power system for stepping said armthrough the contact positions in response to interruptions of saidelectrical current, a reset solenoid for returning said arm means tosaid first position, said reset solenoid having a first connection tosaid second side of said power source, a normally open thermal timedelay switch connected in series with all of the n position contacts,said reset solenoid having a second connection to said time delay switchand to said n+1+m position contact whereby the movable arm isreset fromthe n+1+m position and from said it positions upon prolonged contactwith any of the latter.

4. An electrical alarm system for connection with a community powersystem for giving warning of local and national emergencies, whichcomprises: stepping switch means responsive to at least 72 interruptionsof electrical current in said power system, It being a predeterminednumber greater than 1, said switch means including movable arm meansconnected to the first side of said power system and further includingcontact positions from a first position to at least an n+1-l-m position,m being a predetermined whole number, alarm means connected to the w+lposition contact and to the second side of said power system, relaysolenoid means connected across said power system for stepping said armthrough the contact positions in response to interruptions of saidelectrical current, a reset solenoid for returning said arm means tosaid first position, said reset solenoid having a first connection tosaid second side of said power source, a normally open thermal timedelay switch connected in series with all of the n position contacts,said reset solenoid having a second connection to said time delay switchand to said rr-i-l-l-m position contact whereby the movable arm is resetfrom the n+1+m position and from said n positions upon prolonged contactwith any of the latter, and indicator means connected between said firstposition contact and said second side of said power source for signalingthe presence of said arm means at said first contact position.

5. An electrical alarm system for connection with a community powersystem for giving warning of local and national emergencies, whichcomprises: stepping switch means responsive to at least n interruptionsof electrical current in said power system, 17 being a predeterminednumber greater than 1, said switch means including movable arm means andfurther including contact positions over which said arm means may movefrom a first position to at least an n+1+m position, 771 being apredetermined whole number, a self-contained source of electrical energyconnected at a first side to the n+1 position contact of said switchmeans, electrically operated alarm means connected between the secondside of said source and said movable arm means, relay solenoid meansconnected across said power system for stepping said arm through thesaid contact positions in response to interruptions of said electricalcurrent, a reset solenoid having a first connection to said second sideof said power system, a normally open thermal time delay switchconnected in series with all of the 71 position contacts of said switchmeans, said reset solenoid having a second connection to the said timedelay switch and to said n+1+m position contact whereby the movable armis reset from the n+1+m position and from said it positions uponprolonged contact with the latter.

6. An electrical alarm system for connection with a community powersystem for giving warning of local and national emergencies, whichcomprises: stepping switch means responsive to at least it interruptionsof electrical current in said power system, it being a predeterminednumber greater than 1, said switch means including movable arm means andfurther including contact positions over which said arm means may movefrom a first position to at least an 7z+l+m position, m being apredetermined whole number, a self-contained source of electrical energyconnected at a first side to the n+1 position contact of said switchmeans, electrically operated alarm means connected between the secondside of said source and said movable arm means, relay solenoid meansconnected across said power system for stepping said arm through thesaid contact positions in response to interruptions of said electricalcurrent, a reset solenoid having a first connection to said second sideof said power system, a normally open thermal time delay switchconnected in series with all of the n position contacts of said switchmeans, said reset solenoid having a second connection to the said timedelay switch and to said n+1+m position contact whereby the movable armis reset from the n-l-l-I-m position and from said It positions uponprolonged contact with the latter, and indicator means connected betwensaid first position contact and said second side of said power sourcefor signaling the presence of said arm means at said first contactposition.

7. An alarm system responsive to a predetermined number of successiveinterruptions of a community power supply, comprising: selector switchmeans having at least four successive switching positions, including aninactive rest position, at least two active switching positions and atleast one alarm-actuating position; means connected to said communitypower supply for moving said selector switch means through the saidsuccessive switching positions in response to corresponding successiveinterruptions in said community power occurring in a predetermined timesequence; reset means for automatically returning said selector switchmeans to its said inactive rest position from any of said activeswitching positions which precede said alarm-actuating position of saidcommunity power supply remains energized longer than a predeterminedtime interval following one or more of said interruptions; said resetmeans including a normally open thermal time delay switch coupled tosaid power supply and having a time delay period slightly longer thansaid predetermined time sequence of power interruptions; and said resetmeans further operating through a direct electrical connection with anyof said active switching positions which succeed said alarm-actuatingposition to effect automatic and undelayed return of said selectorswitch means to its said inactive rest position from any of suchsucceeding active switching positions.

References Cited by the Examiner UNITED STATES PATENTS 1,356,626 10/1920Hulit 340-157 1,710,126 4/1929 Vaughan etal. 340 157 1,920,806 8/1933Rich 340167 2,094,733 10/1937 Byrnes 340164 2,811,712 10/1957 Saunders340 310 X 2,912,676 11/1959 Canto 61:31. 340164 FOREIGN PATENTS 257,93711/1927 Great Britain.

519,688 4/1940 Great Britain.

351,523 8/1937 Italy.

360,084 6/1938 Italy.

NEIL C. READ, Primary Examiner.

ELI I. SAX, IRVING L. SRAGOW, Examiners.

1. IN A COMMUNITY ALARM SYSTEM RESPONSIVE TO A PREDETERMINED NUMBER OFINTERRUPTIONS OF THE COMMUNITY POWER SUPPLY WITHIN A PREDETERMINED TIME,A MOVABLE MEMBER, A MOVABLE CONTACT MOUNTED ON SAID MOVABLE MEMBER,BIASING MEANS BIASING SAID MOVABLE MEMBER IN SAID DIRECTION, LATCH MEANSFOR PREVENTING MOVEMENT OF SAID MOVABLE MEMBER IN SAID FIRST DIRECTION,ADVANCING MEANS ENGAGEABLE WITH SAID MOVABLE MEMBER AND BIASED FORMOVEMENT IN A SECOND DIRECTION, ELECTROMECHANICAL MEANS CONNECTED TOSAID COMMUNITY POWER SUPPLY FOR HOLDING SAID ADVANCING MEANS OUT OFENGAGEMENT WITH SAID MOVABLE MEMBER WHEN SAID COMMUNITY POWER SUPPLY ISENERGIZED, A PLURALITY OF FIXED CONTACTS SUCCESSIVELY ENGAGEABLE BY SAIDMOVABLE CONTACT UPON MOVEMENT OF SAID MOVABLE MEMBER, LIMIT MEANS FORLIMITING MOVEMENT OF SAID MOVABLE MEMBER BY SAID ADVANCING MEANS TO THEDISTANCE BETWEEN TWO OF SAID FIXED CONTACTS EACH TIME SAID COMMUNITYPOWER SUPPLY IS DEENERGIZED, AND TIME DELAY MEANS OPERATIVE TO RELEASESAID LATCH IF LESS THAN SAID PREDETERMINED NUMBER OF POWER INTERRUPTIONOCCUR WITHIN SAID PREDETERMINED TIME.